Recently, kitchen garbage, and the like generated in the mansions, and so on as described above are ground by a disposer and discharged together with waste water. Thus, the amount of sludge generated tends to increase, and a problem arises in a method of treating the sludge.
A conventional method of treating sludge is such a system that the sewage discharged from the disposers, kitchens, rest rooms, and so on of mansions, and the like, is stored once in a collective inlet, supplied to a combined water-purifier tank located downstream by a pump, and sequentially purified therein.
In the above treatment method, the sludge having deposited in the collective inlet is also supplied into the combined water-purifier tank and deposits therein. Thus, the treatment capacity of the tank cannot cope with the amount of sludge deposited therein and the deposited sludge must be discharged frequently.
Further, the collected sludge must be subjected to post-treatment such as incineration, and the like, which not only increases the treatment cost of the sludge but also may cause a problem of environmental pollution such as dioxin and the like.
A treatment system as schematically shown in FIG. 4 is in practical use as a treatment method of solving the above problem.
Sewage discharged from a disposer 02 of collective housing 01 such as a mansion or the like is stored once in storage tank 03, supplied to a dehydrator 05 by a pump 04 so as to separate solid contents from liquid contents, the solid contents are charged into a fermenting device 06 and made to compost 07, and the compost 07 is taken out.
In contrast, the discharge water discharged from the dehydrator 05 is fed into an oil-water separation tank 08 so that oil contents are removed therefrom, and then discharged into a public sewer.
The treatment system arranged as described above yet has the following problem. Since the solid contents contained in all the sludge containing sewage in the storage tank 03 is separated from liquid contents using the dehydrator 05, the solid contents are generated in a large amount. Thus, a long time is necessary to make the solid contents into compost in the fermenting tank 06 as well as it is time-consuming to handle and post treat the compost, and a recycling cost is also expensive. Further, since the discharge water the solid contents of which are separated from the liquid contents and which contains the oil contents, is supplied to the oil-water separation tank or the public sewer, a large load is applied thereon. Further, since the dehydrator 05, the fermenting tank 06, and the oil-water separation tank 08 are independently installed, respectively, the size of a treatment apparatus is increased as a whole, and a large installation space is required.
Accordingly, it is an object of the present invention, which was made to solve the above problem, to provide a sewage treatment apparatus for effectively decomposing only solid contents that are obtained by being separated from liquid contents in a short time, substantially reducing the amount of compost and the like generated, decreasing a load applied to a sewage treatment facility, and reducing the overall size of the sewage treatment apparatus by integrating a plurality of processing means as a unit.